ON ANLMAL PARASITES, 103 



another parasite of the same class, Sclerostoma gyngamus. Tlie 

 treatment for " hoose " in calves is to have the animals warmly 

 housed in a dry situation at night, and the affected calves, if any, 

 removed from the healthy ones. Inhalations of sulphurous gas 

 for about fifteen minutes should be given daily until the disease 

 disappears, or, if inhalation is objected to, turpentine may be 

 administered in gruel. The gregarious " maw- worms " {Oxyuris 

 curvula) are common to the horse. Another parasite of this class 

 {Oxyuris vermicular is), the " small thread worm, " inhabits the 

 rectum of man, especially of children. This is the smallest of the 

 intestinal worms of man. A third worm of the kind (Trichoco- 

 phalus dispar) resembles the Oxyuris vermicularis, in inhabiting 

 the large intestine of man. The common round worm {Ascaris 

 Iwmbricoides) also inhabits the intestine of man. It attains a 

 length of several inches, and is usually found in the small intes- 

 tine, but sometimes in other situations. Another lumbricoid of 

 a large size {Ascaris mcgcdocephala) infests the intestines of the 

 horse. As if connecting the parasitic with the free Xematoids, 

 the Ascaris nigrovenosa in succeeding generations is alternately 

 free and parasitic. This Ascaris inhabits the lungs of the frog ; 

 but the young are free, passing from the intestine of the frog into 

 the moist earth, where they grow and develop in the course of a 

 few days into sexually mature animals, the young of these again 

 only attaining a certain stage of development in the earth, and 

 not arri\'ing at sexual maturity until they become parasitic in the 

 lungs of the frog. 



The Leeches ought also to be classed among the parasitic 

 worms properly. They are not internal parasites, however, but 

 live on or upon their host. They form the order Hirudinea in 

 the class Annelida, of which class the earth-worms (Oligochacta) 

 are another order. The Hirudinea includes the common horse 

 leech, and the medicinal leech {Sanguisuga mcdicinalis). 



2. Parasitic Mites. 



The mites belong to the order Acarina, of the class Arachnida. 

 Amongst the parasitic mites are Acarus destructor, a well known 

 species which annoys the naturalist by feeding upon various 

 zoological specimens ; the Hydraclinida:, or water mites, which 

 are parasitic during at least a part of their existence upon water 

 beetles, and other aquatic insects; the Uropodo vegetans and the 

 Gamasus coleoptrcdorum, both found on various beetles ; the 

 Gamasus hilaris, found on field mice ; the Dermanyssus Nitzschii, 

 found in the nostrils of the goat-sucker and other warm-blooded 

 animals ; and the Dermanyssus avium, which infests domestic 

 poultry, canaries, and other cage birds. But the most formidable 

 mite parasite is the Sarcoptis scabiei, or "itch-mite," which is the 



